tests/basics: Add tests to improve coverage of binary.c.

tests/basics/struct_micropython.py

@@ -0,0 +1,20 @@
+# test MicroPython-specific features of struct
+
+try:
+    import ustruct as struct
+except:
+    try:
+        import struct
+    except ImportError:
+        import sys
+        print("SKIP")
+        sys.exit()
+
+class A():
+    pass
+
+# pack and unpack objects
+o = A()
+s = struct.pack("<O", o)
+o2 = struct.unpack("<O", s)
+print(o is o2[0])